KR20120068569A - Light screening apparatus and electronic device including the same - Google Patents

Abstract

PURPOSE: An light screening device and an electronic device having the same are provided to obtain an excellent image quality by preventing light reflection from being generated in one side of a roll-up blade rolled up. CONSTITUTION: An light screening device(100) comprises a base plate(110), a roll-up blade(120), and a driving unit. The base plate comprises a lower electrode. The roll-up blade comprises an upper electrode. The roll-up blade is arranged to correspond to an optical transmission area of the base plate and comprises two or more surfaces having different optical properties. The driving unit is electrically connected to the lower and upper electrodes.

Description

Light screening apparatus and electronic device including the same

The present invention relates to an optical apparatus, and more particularly, to a light screening apparatus and an electronic device having the same.

The light shielding device is a generic term for a device that blocks the passage of light. An optical shutter, which is one of light shielding devices, is a device capable of selectively passing light. For example, the optical shutter provided in the camera may block or open the light that passes through the lens of the camera and reaches the image sensor. By changing the operating speed of the optical shutter and / or the area blocking the camera lens (i.e., the area of the camera lens being opened), the optical shutter can adjust the time and / or amount of light received by the image sensor. have. Light shielding devices, such as optical shutters, can be used in addition to cameras for temporary or permanent light shielding functions or other electronic devices (e.g. optical switching devices) that require selective shielding and passing of light.

Optical shutters include mechanically operated optical shutters and electronic optical shutters. The electronic optical shutter may control the on / off of the image sensor by itself and / or the reception time by controlling the on / off of the image sensor. Since the electronic optical shutter operates in a circuit manner, it is widely used as an optical shutter of a portable digital camera having a limitation in the size of a camera module. However, the electronic optical shutter shows an image drag phenomenon as the number of pixels of the camera module increases.

Recently, as the number of pixels of a camera module mounted on a mobile device increases, interest in a mechanical optical shutter is increasing again. Since electronic devices including camera modules, including digital cameras, have been miniaturized and thinned, mechanical optical shutters must be manufactured with a small size or thickness in order to be employed in electronic devices, and can support very fast response (shuttering) speed. It should be possible. Korean Patent Publication No. 2009-0055996, filed by the same applicant as the applicant of the present application, published on June 30, 2009, "Shutter and Micro Camera Module With Them" has a fast response speed using a plurality of rollup blades. An example of a mechanical optical shutter capable of obtaining is disclosed.

On the other hand, as the manufacturing technology of the display device is developed and the display device is becoming higher in quality, higher in functionality, and in general, most electronic devices are equipped with a display device. In particular, a touch screen using a liquid crystal display (LCD) panel or the like is essentially provided as a display device in a portable electronic device. There are two types of display devices, transmissive and reflective. The former is a display device that uses light that passes through the panel, and the latter is a display device that uses light that reflects the panel. While the transmissive display device is highly visible in a dark environment, the visibility is low in a bright outdoor or indoor environment, and the reflective display device is low in a dark environment but high in a bright environment.

Recently, transflective display devices have been developed that can utilize only the advantages of such transmissive and reflective display devices. Since the transflective display device selectively operates in the reflection mode or the transmission mode according to the brightness of the environment, etc., the transflective display device is particularly useful for mobile electronic devices in which the change of the environment is frequent. Such a transflective display device is typically manufactured by dividing a cell into a reflective structure and a transmissive structure. As a result, the transflective display device has a lower brightness than the conventional single mode display device, that is, a transmissive display device or a reflective display device.

Provided is a light shielding device that prevents the reflection of unwanted light when opened.

Provided is an imaging device that can obtain excellent image quality by preventing the occurrence of noise patterns by using the light shielding device.

Provided is a display device which can be selectively operated between a transmission mode and a reflection mode by using a light shielding device, and in which visibility is not inferior to that of a conventional single mode display device in each mode.

The light shielding device according to an embodiment includes a base plate, a roll-up blade, and a driving unit. The base plate includes a lower electrode and the rollup blade includes an upper electrode. The roll-up blades are arranged to correspond to the light transmitting portions of the base plate, and include at least two surfaces having different optical characteristics. In addition, the driving unit electrically connected to the upper electrode and the lower electrode drives the rollup blade to adjust the amount of light passing through the light transmitting region.

An imaging apparatus according to an embodiment includes an image sensor, a base plate, a rollup blade, and a driver. The base plate comprises a lower electrode and the rollup blade comprises an upper electrode, wherein the light transmitting region of the base plate is arranged to correspond to the image sensor. The roll-up blades are arranged to correspond to the light transmitting portions of the base plate, and include at least two surfaces having different optical characteristics. In addition, the driving unit electrically connected to the upper electrode and the lower electrode drives the rollup blade to adjust the amount of light passing through the light transmitting region.

According to an exemplary embodiment, a display device includes a back light unit, a base plate, a rollup blade, a color filter, and a driver. The base plate includes a lower electrode and is disposed above the backlight unit, and the rollup blade includes an upper electrode. The color filter is disposed above the rollup blade. The roll-up blades are arranged to correspond to the light transmitting portions of the base plate, and include at least two surfaces having different optical characteristics. In addition, the driving unit electrically connected to the upper electrode and the lower electrode drives the rollup blade to adjust the amount of light passing through the light transmitting region.

Since the light shielding device prevents reflection of light from one surface of the rolled up blade, the imaging device having the same can obtain excellent image quality. In addition, when the light shielding device is used, a display device having both a transmissive reflection and excellent visibility can be realized.

1 is a perspective view illustrating a configuration of a light shielding apparatus according to an embodiment, in which light is blocked.
2A is a perspective view illustrating a configuration of a light shielding apparatus according to an embodiment, in which light is passed.
FIG. 2B is a side view of the light shielding device of FIG. 2A.
It is an example of the enlarged view which expanded the dotted line part of FIG. 2B of FIG. 3A.
3B is another example of an enlarged view in which a dotted line portion of FIG. 2B is enlarged.
4 is another example of an enlarged view in which a dotted line portion of FIG. 2B is enlarged.
5A is a perspective view illustrating a configuration of a light shielding device according to another embodiment, in which light is blocked.
5B is a perspective view showing the configuration of a light shielding device according to another embodiment, in which light is passed.
6 is a cross-sectional view schematically illustrating a configuration of an imaging device according to an embodiment including a light shielding device.
7A and 7B are cross-sectional views illustrating a structure of a combined reflection display apparatus according to an exemplary embodiment, in a case of operating in a reflection mode.
8A and 8B are cross-sectional views illustrating a structure of a combined reflection display apparatus according to an embodiment, and is a case of operating in a transmission mode.
FIG. 9A illustrates an example of a method of expressing grayscales of pixels when the display apparatus operates in a transmission mode.
FIG. 9B illustrates an example of a method of expressing grayscales of pixels when the display apparatus operates in the reflective mode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms used are terms selected in consideration of the functions in the embodiments, and the meaning of the terms may vary depending on the user, the intention or custom of the operator, and the like. Therefore, the meaning of the terms used in the embodiments to be described later, according to the definition if specifically defined herein, and if there is no specific definition should be interpreted to mean generally recognized by those skilled in the art. And if the first material layer is formed on the second material layer, it is not only the case that the first material layer is formed directly on the second material layer (directly on), but also explicitly exclude Unless otherwise, it should be construed to include all other third material layers interposed between the second material layer and the first material layer.

1 and 2A are perspective views showing the configuration of the light shielding apparatus 100 according to an embodiment, and a side view of the light shielding apparatus 100 of FIG. 2A of FIG. 2B. 1, 2A, and 2B, the light shielding device 100 includes a base plate 110, a rollup blade 120, and a driving unit 130 ( However, for the convenience of illustration, the illustration of the driver 130 is omitted in FIGS. 2A and 2B). The light shield device 100 may itself function as a single optical shutter (see FIGS. 7A and 7B) or may be part of constituting an optical shutter (see FIGS. 5A and 5B). 1 illustrates a state in which the light shielding device 100 is driven to block light, and the base plate 110 and the roll-up blade 120 are separately shown for convenience of description. 2A and 2B illustrate a state in which the light shielding device 100 of FIG. 1 passes light.

The base plate 110 has a light transmitting portion 110a through which light can pass. The light transmitting region 110a may be transparent or translucent. The light transmitting region 110a corresponds to a light transmitting portion through which the light can pass in a state where the rollup blade 120 is rolled up, that is, in a rolled up state, as shown in FIG. 2A. For example, when the light shielding device 100 functions as an optical shutter of the imaging device, the light transmitting region 110a of the base plate 110 is located on the light path of the imaging device to transmit light. Light passing through region 110a reaches the image sensor via the optical lens. When the rollup blade 120 is driven as shown in FIG. 1, the light transmitting region 110a is partially or entirely covered by the rolled up blade 120 so that the amount of light passing through the light transmitting region 110a is increased. Adjustable An area of the base plate 110 other than the light transmitting area 110a may be optically transparent or opaque.

The shape of the base plate 110 may have a flat shape as in the example shown in FIG. 1, which is merely exemplary. The base plate 110 may have various other forms (eg, a curved, banded, or curved shape) without limitation as necessary. In addition, the shape of the light transmitting region 110a is not particularly limited, and may be rectangular, circular, elliptical, or polygonal. The base plate 110 includes a substrate 112 and a lower electrode 114. The substrate 112 may be formed of a transparent or semitransparent material as a whole, or may be formed of a transparent or semitransparent material in at least a portion of the substrate 112 including the light transmitting region 110a. Substrate 112 may be a glass substrate, but is not limited thereto, and may be formed of other materials, such as quartz or plastic, such as quartz, plastic, or silica. It may be.

The lower electrode 114 may be transparent or translucent and formed of an electrically conductive material. For example, the lower electrode 114 may be formed of indium tin oxide (ITO) or transparent or translucent zinc oxide (ZnO), tin oxide (SnO ₂ ), carbon nanotube (CNT), and conductive material. It may be formed of a polymer (conductive polymer) or the like. The lower electrode 114 is electrically connected to the driving unit 130 and functions as one of driving electrodes for driving the light shielding device 100, more specifically, the roll-up blade 120.

The lower electrode 114 may be formed on the upper surface of the substrate 112 or may be embedded in the substrate 112. The lower electrode 114 may be formed to cover the entire surface of the light transmissive region 110a or may be formed only at a portion of the lower electrode 114 to have a predetermined pattern in the light transmissive region 110a. In the former case than in the latter case, the lower electrode 114 can generate a greater attraction force with the upper electrode of the rollup blade 120, so that the rollup blade 120 can be driven and unrolled more quickly. However, the present embodiment is not limited thereto, and the lower electrode 114 may be formed only in a portion of the light transmitting region 110a or may be formed over the light transmitting region 110a and its peripheral region.

The roll-up blade 120 exists in a state of being rolled up with a predetermined curvature unless a driving force is applied between the base plate 110 (see FIGS. 2A and 2B). In this state, at least the transparent region 110a of the base substrate 110 is exposed, and light incident from the outside may pass through the transparent region 110a. On the other hand, when a predetermined driving force is applied between the roll-up blade 120 and the base plate 110 from the drive unit 130, the roll-up blade 120 is in an extended state (see FIG. 1). In this state, the light transmitting region 110a of the base plate 110 is covered by the rollup blade 120, and light incident from the outside is blocked. Unlike that shown in FIG. 1, it is apparent that the incident light may be partially blocked by the roll-up blade.

In order to block light, the rollup blade 120 may include one or more layers of materials having properties that light does not pass through. The light shielding device 100 has only one roll-up blade 120 or a light transmitting area having a size that can cover the entire light transmitting area 110a as shown in FIGS. 1, 2A, and 2B. A plurality of rollup blades may also be included to cover area 110a in area (see FIGS. 5A and 5B).

The rollup blade 120 may be divided into a fixing portion 120a and a moving portion 120b. The roll-up blade 120 is fixed at the fixing part 120a, and may be fixed to one side of the base plate 110 (outside of the light transmitting area 110a) as shown. Alternatively, the fixing part 120a may be fixed to another structure (not shown) disposed outside or on the upper side of the base plate 110. The remaining part of the roll-up blade 120 except for the fixing part 120a is the movable part 120b which is extended or rolled up under the control of the driving part 130. For example, when a driving voltage is applied by the driving unit 130 to form potentials opposite to each other between the base plate 110 and the rollup blade 120, an attraction force is formed between the base plate 110 and the rollup blade 120. By this function, the movable part 120b which was in a rolled up state is unfolded to cover the light transmitting region 110a. When the applied driving voltage is released, the movable unit 120b is restored to the rolled up state.

The rollup blade 120 may include at least two surfaces having different optical characteristics. Two or more surfaces having different optical properties may be arranged to correspond to each other (see FIG. 3A) or may be disposed on the same side (not shown). Here, having different optical properties is not limited to using heterogeneous materials having different optical properties. For example, even when the same material is used, surfaces having different optical properties may be formed by different surface treatments and / or patterning.

In addition, the rollup blade 120 has one surface, more specifically, the outer circumference surface 122a of the rollup blade 120 has a light reflection in a state where the rollup blade 120 is rolled up as shown in FIGS. 2A and 2B. It is possible to form an anti-reflection surface to prevent. Here, the "anti-reflection surface" refers to a structure in which the light reflected from the surface is minimized. The outer circumferential surface 122a of the roll-up blade 120 forming the anti-reflection surface is formed like an optical black surface. It looks black

For example, low reflectance at the surface can be one condition that can form an antireflective surface. However, in the case where the light transmittance is high and there is a relatively large amount of light coming back by internal reflection, it is not possible to form the antireflection surface even though the surface reflectance is low. Existing anti-reflection coating (ARC) can improve the light transmission to reduce surface reflection, thereby forming an anti-reflection surface. However, on the opposite side of the anti-reflective coating (ARC), another layer of material (e.g., the upper electrode layer 124 in the case of the roll-up blade 120) is formed of a metallic material, which causes internal reflection by the upper electrode layer 124. There is a lot of light coming out. Therefore, a roll-up blade having only an antireflection coating (ARC) added to the outer circumferential surface cannot minimize the amount of reflected light and thus cannot form an antireflection surface.

When the outer circumferential surface 122a of the rollup blade 120 does not form an antireflection surface, a substantial portion of the light incident to the rollup blade 120 in the rolled up state is reflected on the outer circumferential surface 122a. Some of the reflected light may be reflected back to the outside but reflected off of some other light, in particular on the side of the rolled up rollup blade 120 (part of the rollup blade 120 perpendicular to the light transmitting region 110a). Light may pass through the light transmitting region 110a. The reflected light passing through the light transmitting region 110a is an unwanted light component. For example, when the light shielding device 110 is used as an optical shutter of the imaging device, the reflected light is received by the image sensor. It can also produce ghost images.

One way to prevent the noise pattern from occurring is to place the roll up blade 120 relatively far from the light transmissive region 110a so that the reflected light does not pass through the light transmissive region 110a. However, in this case, since the size of the rollup blade 120 is inevitably increased, the response speed of the rollup blade 120 is lowered. However, when the outer circumferential surface 122a of the roll-up blade 120 forms an anti-reflection surface as in the present embodiment, such a noise pattern may be prevented from occurring so as to prevent deterioration of image quality and response speed. The problem of degradation does not occur.

One method for causing one surface of the rollup blade 120 including the upper electrode layer 124 to form an antireflective surface, wherein the antireflective surface of the rollup blade 120 includes an optical black layer 122. To do that. The light black body layer 122 is a material layer that absorbs and disappears visible light passing through. In this case, the rollup blade 120 may include a light black body layer 122 formed of a single material film and an upper electrode layer 124 formed on the light black body layer 122. The light black body layer 122 may be a single layer structure of a single material film (see FIG. 3A) or a multilayer structure formed of the same material or different materials (see FIG. 3B).

A significant portion of the light incident on the light blackbody layer 122 enters the interior of the rollup blade 120 without being reflected off the surface. Most of the light that enters the inside of the roll-up blade 120 is absorbed and disappears while passing through the light black body layer 122. Light extinguished from the light black body layer 122 includes not only incident light from the outside but also light reflected internally by the upper electrode layer 124 and exiting toward the outer circumferential surface 122a. Accordingly, the roll-up blade 120 may form an anti-reflection surface 122a on one surface of the light black body layer 122, that is, the surface opposite to the side where the upper electrode layer 124 is formed.

Another method for causing one surface of the rollup blade 120 including the upper electrode layer 124 to form an antireflection surface is a light absorbing layer in which the rollup blade 120 weakens the intensity of light (eg, visible light). It is to have a multilayer structure including an absorbing layer). The multilayer structure including the light absorbing layer functions as an absorption type antireflection structure. In this case, the light that enters the interior without being reflected from the surface is weakened primarily through the light absorbing layer, and the light that is reflected internally by the upper electrode layer 124 and returned is again intensified while passing through the light absorbing layer again. It can be weaker. In addition, the roll-up blade 120 has a multilayer structure of at least three layers or more so that the light reflected from the surface and the light reflected from the inside cause destructive interference, so that the absorption type anti-reflection structure has an anti-reflection surface of the roll up blade 120. The light coming from can be minimized.

And the other surface of the roll-up blade 120, more specifically, the inner circumference surface (inner circumference surface, 124a) of the roll-up blade 120 in a state in which the roll-up blade 120 is rolled up, as shown in Figure 2a and 2b In a state where the rollup blade 120 is extended as shown in FIG. 1, the upper surface 124a of the rollup blade 120 may form a reflection surface that reflects light. As such, the surfaces with different optical properties (reflective and antireflective surfaces as exemplarily described above) may be applied to the symmetrical surfaces of the rollup blade 120 (ie, the outer circumferential surface 122a and the inner circumferential surface 124a). Each may be formed (see FIG. 3A) or may be formed on the same side (eg, the outer circumferential surface 122a). However, it is not necessary for all kinds of light shielding devices to form a reflective surface on one surface of the rollup blade 120, and is reflected from the reflective surface of the rollup blade 120 while covering the light transmitting region 110a. It may be provided in an electronic device (eg, a display device for both reflection and transmission) using light, which will be described later.

Here, "reflective surface" can simply refer to only those with high reflectance on the surface. In addition, not only the surface reflectance is high, but also the multilayer structure in which the light that is not reflected from the surface and enters the light is not reflected but is also reflected back to form a reflective surface. Therefore, "the inner circumferential surface 124a of the rollup blade 120 forms a reflective surface" may refer only to the surface characteristics of the rollup blade 120 having a high surface reflectivity of the inner circumferential surface 124a, and in addition, the rollup blade ( It may also refer to having one or more layers of material that enable to maximize the light coming back from the inner circumferential surface 124a of 120 and / or having a reflective structure that can achieve this effect.

3A and 3B illustrate the structure of the roll-up blade 120 as an example, and are enlarged views of dotted lines of the roll-up blade 120 of FIG. 2B. Since the rollup blade 120 of FIG. 2B is rolled up in the upper left direction, the right side surface of the rollup blade 120 in FIGS. 3A and 3B corresponds to the outer circumferential surface 122a of the rollup blade 120 of FIG. 2B. 3A and 3B, the roll-up blade 120 includes an optical black layer 122 contacting the base plate 110 and an upper electrode layer 124 stacked thereon. can do.

Referring to FIG. 3A, the light black body layer 122 may be a single material layer having at least one surface (right side) forming an anti-reflection surface. The material forming the light black body layer 122 may be a conductive material or an electrically insulating material such as a dielectric or polymer having the above-described optical properties. However, when the light black body layer 122 is formed of a conductive material, an insulating layer formed of an insulating material may be further formed on the bottom surface of the light black body layer 122 and / or the top surface of the base plate 110. .

The light black body layer 122 may be formed of a material having a low surface reflectance and a large extinction coefficient, that is, a material having a considerable amount of light absorption. In general, the incident light reflects off the surface and the remaining light enters the medium, and the medium disappears in proportion to the extinction coefficient and only the remaining light exits. According to this, even if the extinction coefficient is large, when the surface reflection coefficient is large, the amount of light that is absorbed and extinguished is not large. Therefore, the material forming the light black body layer 122 should generally be a material having a large extinction coefficient, but also a material having a small surface reflection coefficient. For example, a material such as aluminum (Al) or silver (Ag) has a larger extinction coefficient than chromium (Cr) or molybdenum (Mo) but has a large surface reflection coefficient. Inappropriate.

In addition, the right surface of the light black body layer 122 may have a rough surface so as to lower the surface reflectance of the light black body layer 122. There is no particular limitation on the type of rough surface. For example, fine protrusions such as embossing may be formed on the surface of the light black body layer 122. However, the present invention is not limited thereto, and any shape (not necessarily a regular pattern) capable of lowering the surface reflectance of light may be a rough surface.

The upper electrode layer 124 is formed of an opaque metal such as chromium (Cr), aluminum (Al), gold (Au), molybdenum (Mo), copper (Cu), or a combination thereof, or an opaque and conductive polymer. It can be formed as. In particular, the upper electrode layer 124 may be formed by selecting a thickness and / or a material such that the intensity of light reflected from the upper electrode layer 124 and coming back from the surface of the light black body layer 122 is very small. Light that passes through the light black body layer 122 and is reflected from the upper electrode layer 124 again passes through the light black body layer 122 and is mostly extinguished and / or reflected from the surface of the light black body layer 122. May cause destructive interference.

In addition, the light black body layer 122 and the upper electrode layer 124 of the roll-up blade 120 may be formed to have different residual stresses. More specifically, the upper electrode layer 124 may be formed to have a tensile residual stress. The photo black body layer 122 may be formed to have a compressive residual stress, no residual stress, or a tensile residual stress but a tensile residual stress smaller in size than the upper electrode layer 124. Due to the residual stress difference between the upper electrode layer 124 and the photo black body layer 122, when the driving voltage is not applied, the movable part 120b of the rollup blade 120 is rolled up (see FIGS. 2A and 2B). do. And by adjusting the residual stress difference, it is possible to adjust the curvature of the movable portion (120b) is rolled up.

On the contrary, when a driving voltage is applied from the driver 130 and a predetermined driving force (force) is applied between the lower electrode 114 and the rollup blade 120, more specifically, the upper electrode layer 124, the rollup blade 120 is applied. The movable part 120b of () is unfolded, and covers the light transmission area | region 110a of the base board 110 (refer FIG. 1). The driving force may be electrostatic force acting between the lower electrode 112 and the upper electrode layer 124, but is not limited thereto. For example, when the upper electrode layer 124 includes a piezoelectric layer, in addition to the electrostatic force, the piezoelectric driving force may also be a driving force for driving the movable portion 120b of the rollup blade 120.

Referring to FIG. 3B, the light black body layer 122 may have a multilayer structure in which a plurality of material layers are stacked. Here, the plurality of material layers may be three or more layers. For example, the light black body layer 122 may include a first phase compensation layer 1222 contacting the base plate 110, a light absorbing layer 1224 formed on the first phase compensation layer 1222, and A second phase compensation layer 1226 formed on the light absorbing layer 1224 may be included.

The first phase compensation layer 1222 may be formed of an electrically insulating material because it contacts the base plate 110, more specifically, the lower electrode 114 of the base plate 110. In addition, the first phase compensation layer 1222 may perform a function of preventing initial reflection of light L1 incident on the light absorbing layer 1224 from the atmosphere. To this end, the first phase compensation layer 1222 is a material that can mitigate the change in the refractive index between the air and the light absorbing layer 1224, that is, larger than the refractive index of the air, but rather than the refractive index of the light absorbing layer 1224. It may be formed of a material having a small refractive index. For example, when a metal material such as chromium (Cr), molybdenum (Mo), or the like is used as the light absorbing layer 1224, the first phase compensation layer 1222 may be a dielectric such as silicon oxide. It can be formed as. The first phase compensation layer 1222 may be formed of a single layer or two or more layers each formed of the same material or different materials.

In addition, the first phase compensation layer 1222 may also perform a function of adjusting a phase of light passing through the first phase compensation layer 1222. For example, when the first phase compensation layer 1222 is formed of silicon oxide, the light L2 reflected by the light absorbing layer 1224 and the light L3 reflected by the upper electrode layer 124 may cause destructive interference. The thickness of the first phase compensation layer 1222 may be adjusted to cause it. Of course, since the light L3 reflected from the upper electrode layer 124 also passes through the second phase compensation layer 1226, the thickness of the first phase compensation layer 1222, which may cause destructive interference, may be the second phase compensation layer ( It may vary depending on the degree of phase adjustment by 1226).

The light absorbing layer 1224 functions to absorb light to weaken the intensity. To this end, the light absorption layer 1224 may be formed of a translucent metal material having a large absorption coefficient, such as chromium (Cr), molybdenum (Mo), or a combination thereof. Alternatively, the light absorbing layer 1224 may be formed of a dielectric or polymer having a relatively large absorption coefficient. The light L1 incident on the rollup blade 120 decreases in intensity every time it passes through the light absorbing layer 1224. When only a thin thin film is added to the upper electrode 124 to cause destructive interference, it is difficult to achieve antireflection over the entire band of visible light, but the light absorbing layer 1224 weakens the intensity of the light passing through the broadband. To prevent reflections. The light absorbing layer 1224 may also be formed of a single layer or two or more layers each formed of the same material or different materials.

The second phase compensation layer 1226 may be formed of an electrically insulating material for electrical insulation between the light absorbing layer 1224 and the upper electrode layer 124. In addition, like the first phase compensation layer 1222, the second phase compensation layer 1226 may also perform a function of adjusting a phase of light passing therethrough. To this end, the second phase compensation layer 1226 may be formed of the same material as the first phase compensation layer 1222, for example, a dielectric such as silicon oxide. The thickness of the second phase compensation layer 1226 may be adjusted such that light L2 reflected from the light absorbing layer 1224 and light L3 reflected from the upper electrode layer 124 may cause destructive interference. The second phase compensation layer 1226 may also be formed of a single layer or two or more layers each formed of the same material or different materials.

The upper electrode layer 124 is an opaque metal layer formed of chromium (Cr), aluminum (Al), gold (Au), molybdenum (Mo), copper (Cu), or a combination thereof, or an opaque and conductive polymer. It can be formed as. There is no restriction | limiting in the kind of conductive polymer in the latter case, Even if it is a transparent conductive polymer, it can have opaque characteristic by methods, such as a coloring. The upper electrode layer 124 may serve as a reflector for returning light to the light black body layer 122. This is to minimize the light reflected from the outer circumferential surface of the rollup blade 120 by inducing a destructive interference between the light L3 reflected by the upper electrode layer 124 and the light L2 reflected by the light absorbing layer 1224. .

When the driving voltage is not applied from the driver 130, the first phase compensation layer 1222 of the rollup blade 120 may be maintained so that the movable part 120b of the rollup blade 120 is rolled up (see FIG. 2A). ), The light absorbing layer 1224, the second phase compensation layer 1226, and the upper electrode layer 124 may be formed to have different residual stresses. More specifically, the first phase compensation layer 1222 to the upper electrode layer 124 is formed to have a tensile residual stress that increases sequentially or the first phase compensation layer 1222 has a compressive residual stress and the upper electrode layer 124 Has a tensile residual stress, and the light absorbing layer 1224 and the second phase compensation layer 1226 may each be formed to have a smaller tensile residual stress and / or a compressive residual stress.

Due to the residual stress difference between the upper electrode layer 124, the second phase compensation layer 1226, the light absorbing layer 1224, and the first phase compensation layer 1222, if the driving voltage is not applied, the rollup blade 120 is applied. The movable portion 120b is in a curled state. In this case, the curvature of the movable part 120b rolled up can be adjusted by adjusting a residual stress difference. When a driving voltage is applied from the driver 130 and a predetermined driving force (force) is applied between the lower electrode 114 and the rollup blade 120, more specifically, the upper electrode layer 124, the rollup blade 120 is applied. The movable portion 120b of the substrate 120 is extended to cover the light transmitting region 110a of the base plate 110. The driving force may be electrostatic force acting between the lower electrode 112 and the upper electrode layer 124, but is not limited thereto.

3A and 3B, at least one surface (left side in FIGS. 3A and 3B) of the upper electrode layer 124 may form a reflection surface. To this end, the upper electrode layer 124 may be formed of a conductive material having a high surface reflectance. Alternatively, as shown in FIG. 4, the upper electrode layer 124 is formed on one surface of the conductive layer 1242 and the conductive layer 1242 formed of a conductive material, that is, on the surface opposite to the surface on which the light black body layer 122 is formed. The light reflection layer 1244 may be formed of a material having a high surface reflectance. In this case, the outer surface of the light reflection layer 1244 becomes a reflecting surface. As will be described later, the light shielding device including the upper electrode layer 124 having the light reflecting layer 1244 may be used for a display device that combines reflection and transmission.

1, 2A, and 2B, the driving unit 130 is electrically connected to the lower electrode 114 of the base plate 110 and the upper electrode 124 of the rollup blade 120. More specifically, the driving unit 130 may be electrically connected to the lower electrode 114 of the base plate 110 and the upper electrode layer 124 of the rollup blade 120. In addition, the driving unit 130 may apply a driving voltage having a potential opposite to the lower electrode 114 and the upper electrode layer 124 so that the movable portion 120a of the roll-up blade 120 may be unfolded.

The roll-up blade 120 according to the above-described embodiment has been observed in actual experiments that the reflectance of visible light at the outer circumferential surface 120a forming the anti-reflection surface is considerably low. More specifically, conventional roll-up blades in which the lower insulating layer is formed of silicon nitride (thickness about 300 nm) and the upper electrode layer is formed of aluminum (Al, about 500 nm thick) have a wavelength of visible light for all incident angles. Reflectivity in the range is about 60-90%. On the other hand, a roll-up blade 120 having an absorption type antireflection structure as shown in FIG. 3B, more specifically, a first phase compensation layer 1222 formed of silicon oxide (about 90 nm thick) and a light absorption layer 1224 formed of chromium Thickness of about 7 nm), the second phase compensation layer 1226 formed of silicon oxide (about 90 nm thick), and the top electrode layer 124 formed of chromium (about 60 nm thick) of the roll-up blade 120 has all angles of incidence. The reflectivity was about 20% or less in the visible light wavelength range.

5A and 5B are perspective views illustrating a light shielding device 200 according to another embodiment, in which FIG. 5A shows a state in which the light shielding device 200 blocks light and FIG. 5B shows a light shielding device 200. ) Shows a state in which light passes. The light shielding device 200 of FIGS. 5A and 5B can be used as a mechanical optical shutter for an imaging device such as a digital camera, which is merely exemplary.

In addition, the light shielding device 200 includes a plurality of roll-up blades 220, and the base plate may have a shape in which a movable portion of each of the plurality of roll-up blades 220 extends radially from the center of the light transmitting region 210a. A fixed end of each of the plurality of roll-up blades 220 is fixed around the light transmitting region 210a so as to cover the light transmitting region 210a of the 210 by area division. In this case, the light shielding device 100 of FIGS. 1, 2A, and 2B may be an enlarged view of only one roll-up blade constituting the light shielding device 200 shown in FIGS. 5A and 5B. . Hereinafter, the light shielding device 200 will be described based on the difference from the light shielding device 100 described above.

5A and 5B, the light shielding device 200 includes a base plate 210 having a light transmitting region 210a. The shape of the light transmitting region 210a may be circular, elliptical, regular polygonal, or the like. The base plate 210 includes a transparent substrate 212 and a lower electrode 214 formed on the transparent substrate 212.

The light shielding device 200 includes a plurality of rollup blades 220. Each of the plurality of roll-up blades 220 forms an anti-reflection surface on the outer circumferential surface 222a in a rolled up state as illustrated in FIG. 5B. To this end, each of the roll-up blades 220 may have an antireflection structure including the light black body layer 222. In addition, each of the plurality of roll-up blades 220 may have an upper surface 224a to form a reflective surface in an unfolded state as illustrated in FIG. 5A.

The fixed end of each of the plurality of roll-up actuators 220 is fixed on the base plate 210 to form a circular, elliptical or regular polygon around the outer periphery of the light transmitting region 210a. In addition, when the plurality of roll-up blades 220 are driven to extend the respective movable portions, each movable portion extends radially from the center of the light transmitting region 210a (for example, at the center of the light transmitting region 210a). Each roll-up blade 220 may cover the light transmitting region 210a in an area divided into a fan shape having a central angle of a predetermined size or a triangular shape having a vertex of a predetermined size. In this case, a predetermined gap may be formed between the adjacent rollup blades 220 and at least between the moving parts of the adjacent rollup blades 220. In addition, a portion of the movable portion adjacent to the fixed end may be integral with each other without a gap such that mechanical coupling may be made between adjacent rollup actuators 220.

In addition, the light shielding device 200 includes a drive unit 230 electrically connected to the base plate 210 and the plurality of rollup blades 220 to control the movable portions of the plurality of rollup blades 220 to be unfolded. . In this case, the driving unit 230 may drive the plurality of roll-up blades 220 to be unfolded at the same time or to be unfolded individually. In addition, the driving unit 230 may adjust the degree to which the plurality of roll-up blades 220 are extended to adjust the degree to which the light transmitting region 210a is opened.

In the light shielding device 200 having such a structure, when a driving voltage is not applied from the driving unit 230, as shown in FIG. 5B, the movable portion of each roll-up blade 220 forms the light black body layer 222 forming the same. It may be a single layer structure or a multi-layered structure of three or more layers) and is curled due to the residual stress difference between the upper electrode layer 224. That is, the movable portion of each roll-up blade 220 is rolled up outward from the center of the light transmitting region 210a to expose the light transmitting region 210a of the base plate 210. When a driving voltage is applied between the base plate 210 and the rollup blade 220, the movable portion of each rollup blade 220 is extended to cover the light transmitting region 210a, thereby blocking the passage of light.

6 is a cross-sectional view schematically illustrating a configuration of an imaging device according to an embodiment including a light shielding device. Referring to FIG. 6, the imaging device A includes a light shielding device 310, a lens unit 320, and an image sensor 330.

The light shielding device 310 may be the same as, for example, the light shielding device 200 illustrated in FIGS. 5A and 5B, but is not limited thereto. However, in FIG. 6, illustration of the driving unit of the light shielding device 310 is omitted, which is merely for convenience of illustration. The driving unit of the light shielding device 310 controls the driving of the roll-up blade 314 so that the plurality of roll-up blades 314 are rolled up or unrolled, through which light is received or received by the image sensor 330. It can block the light. In addition, the driving unit of the light shielding device 310 may adjust the amount of light received by the image sensor 330 by adjusting the time that the rollup blade 314 is rolled up and / or the degree of the rollup blade 314 being unfolded. have. The outer circumferential surface 314a of the rollup blade 314 forms an antireflection surface.

Spacer frame 316 to protect the rollup blade 314 on the base plate 312 of the light shielding device 310, more specifically on the peripheral region of the base plate 312 on which the rollup blade 314 is not disposed. ) May be arranged. Alternatively, a transparent cover (not shown) that may cover the entire base plate 312 may be provided on the base plate 312 instead of the spacer frame 316. In addition, the base plate 312 of the light shielding device 310 may be further provided with an optical component 318 such as a filter, a lens, etc. used to adjust the light passing through the light transmission region.

The lens unit 320 is an imaging optical system that allows the light passing through the light transmitting region of the light shielding device 310, more specifically, the base plate 312, to form an image in the image sensor 330. The lens unit 320 may be composed of one or a plurality of lenses, and may include means for adjusting the focal length of the imaging device A. FIG. Although not shown in the drawings, another lens unit may be further provided on the upper side of the light shielding device 310.

The image sensor 330 receives the light passing through the light transmitting area of the base plate 312 to generate an image, and may have a number of pixels. The type of the image sensor 330 is not particularly limited. For example, the image sensor 330 may be a CMOS image sensor (CMOS) image sensor or a charge coupled device (CCD). In addition, when the plurality of roll-up blades 314 are driven and unrolled, light does not pass through the light transmitting region, and thus no light is received by the image sensor 330.

Next, a description will be given of a reflective transmission display device using the above-described light shielding device. 7A, 7B, 8A, and 8B are cross-sectional views illustrating a structure of a combined transmissive display device according to an embodiment, and FIGS. 7A and 7B illustrate a case in which a combined transmissive display device operates in a reflective mode. 8A and 8B illustrate a case in which the reflective display device is operated in a transmission mode. 7A, 7B, 8A, and 8B, the display apparatus B includes a light shielding device 410, a backlight unit (BLU, 420), and a color filter (430). It includes. The light shielding device 410 may be the same as the light shielding device 100 shown in FIGS. 1, 2A, and 2B, for example. 7A and 7B, illustration of the driving unit of the light shielding device 410 is omitted, which is merely for convenience of illustration. The backlight unit 420 and the color filter 430 are not particularly limited in configuration or type.

7A, 7B, 8A, and 8B may schematically illustrate the configuration of unit pixels of the display device B, which indicates that the light shielding devices 410 are arranged one per pixel. This does not necessarily mean that the light shielding device 410 must be disposed in every pixel. Here, the 'unit pixel' may be for the display surface or for the color filter 430. In the former case, the color filter 430 of the unit pixel includes all the RGB. In the latter case, the color filter 430 of the unit pixel may include only one color of the RGB.

When operating in the reflection mode as illustrated in FIGS. 7A and 7B, the display device B uses light incident from the outside and reflected by the light shielding device 410 as a light source. To this end, the light shielding device 410 of the display device B may include a roll-up blade 414 whose upper surface 414a forms a reflective surface (see FIG. 4). When operating in the reflective mode, the backlight unit 420 may be turned off. In the reflective mode, as shown in FIG. 7A, when the roll-up blade 414 is in an unfolded state, most of the incident light is reflected and returned, so that the pixel is in a bright state. On the other hand, when the roll-up blade 414 is in the rolled-up state as shown in FIG. 7B in the reflection mode, there is no reflected light or the pixel is dark. In addition, if the lower surface of the roll-up blade 414 forms an anti-reflection surface, unnecessary reflected light may be generated from the rolled-up roll-up blade 414 to prevent the visibility of the display from deteriorating.

When operating in the transmissive mode as shown in FIGS. 8A and 8B, the display device B uses light emitted from the backlight unit 420 as a light source. As shown in FIG. 8A, when the roll-up blade 414 is in a rolled-up state, light emitted from the backlight unit 420 mostly goes out. In this case, if the lower surface of the rollup blade 414 forms an antireflection surface, unnecessary reflected light may be generated from the rolled up rollup blade 414 to prevent the visibility of the display from deterioration. As shown in FIG. 8B, when the roll-up blade 414 is in the unfolded state, light emitted from the backlight unit 420 is blocked, and the corresponding pixel is dark.

The driving portion of the light shielding device 410 controls the driving of the rollup blade 414 such that the rollup blade 414 is rolled up or unrolled. As a result, the display device B may pass or block the light emitted from the backlight unit 420 per unit pixel (when in the transmissive mode), and may maximize the light incident from the outside or prevent reflection from occurring. (When in reflective mode). In addition, the driving unit may individually control driving of the plurality of rollup blades 414 arranged corresponding to the pixels arranged in the matrix form.

In addition, the driving unit of the light shielding device 410 controls the amount of time the roll-up blade 414 is rolled up and / or the extent to which the roll-up blade 414 is unfolded, and thus the amount of light emitted from the backlight unit 420 or the roll-up blade. The amount of light reflected from the upper surface of 414 may be adjusted. More specifically, the brightness of each pixel in the transmissive mode is proportional to the time the rollup blade 414 is in the rolled up state, and in reflection mode the brightness of each pixel is proportional to the time the rollup blade 414 is in the extended state. do. Therefore, the driving unit of the light shielding device 410 may express the gray level of the corresponding pixel by adjusting the average time that the movable part of the roll-up blade 414 is stretched per frame (predetermined unit time).

9A and 9B illustrate an example of a method of expressing gray levels of pixels when the display apparatus B operates in a transmission mode and a reflection mode, respectively. Referring to FIG. 9A, when the display device B operates in the transmissive mode (see FIGS. 8A and 8B), the brightness of the pixel is the average time (a)>(b)> (c) to which the driving voltage is applied. That is, it can be seen that the roll-up blade 414 per frame is inversely proportional to the average time that it is in an extended state. Referring to FIG. 9B, when the display device B operates in the reflection mode (see FIGS. 7A and 7B), the brightness of the pixel is the average time (a)>(b)> (c) when the driving voltage is applied. , Ie, proportional to the average time that the roll-up blade 414 per frame is in the unfolded state. 9A and 9B, since the driving voltage signals for expressing the same grayscale are opposite to each other in the transmission mode and the reflection mode, the display device B may be obtained by simply inverting the driving voltage signals applied from the driver. It can be seen that is possible to switch between the transmission mode and the reflection mode.

The above description is only an embodiment of the present invention, and the technical idea of the present invention should not be construed as being limited by this embodiment. The technical idea of the present invention should be specified only by the invention described in the claims. Therefore, it will be apparent to those skilled in the art that the above-described embodiments may be implemented in various forms without departing from the spirit of the present invention.

100, 200, 310, 410: light shielding device
110, 210, 312: base plate
110a, 210a: light transmitting region
112, 212: substrate
114, 214: lower electrode
120, 220, 314, 414: Rollup Blade
120a: fixed part
120b: moving part
122, 222: light black body layer
124 and 224: upper electrode layer
1222: first phase compensation layer
1224: light absorbing layer
1226: second phase compensation layer
130, 230: drive unit
320: lens unit
330: image sensor
420: backlight unit
430 color filter

Claims (33)

A base plate including a lower electrode;
A rollup blade including an upper electrode; And
A driving unit electrically connected to the lower electrode and the upper electrode,
The roll-up blade is disposed corresponding to the light transmitting area of the base plate,
The roll-up blade includes at least two surfaces having different optical properties. The method of claim 1,
The driving unit drives the roll-up blade to adjust the amount of light passing through the light transmission region. The method of claim 1,
One of the at least two faces is an anti-reflection surface,
And the anti-reflection surface prevents reflection of light incident on an outer circumference surface of the roll-up blade. The method of claim 3,
The anti-reflection surface is a light shielding device including a black body layer of a single layer structure or a multilayer structure. The method of claim 4, wherein
The black body layer is a light shielding device having a multilayer structure formed of a heterogeneous material. The method of claim 3,
The anti-reflection surface is a light shielding device of 20% or less reflectance of visible light. The method of claim 3,
The roll-up blade is a light shielding device having a multi-layered structure of three or more layers. The method of claim 7, wherein
And the rollup blade comprises a metal absorbing layer. The method of claim 8,
The metal absorbing layer is formed of chromium (Cr) or molybdenum (Mo) or formed of a combination of chromium and molybdenum. The method of claim 7, wherein
And the rollup blade comprises a light absorbing layer interposed between two or more phase compensation layers. The method of claim 7, wherein
And the rollup blade comprises a layer of dielectric material. The method of claim 1,
And the upper electrode is formed of one or two or more combinations selected from the group consisting of chromium (Cr), aluminum (Al), gold (Au), molybdenum (Mo), and an opaque polymer. The method of claim 1,
The rollup blade includes a fixing portion and a moving portion,
And the fixing part is fixed to the outside of the light transmitting region, and the movable part is rolled up toward the fixing part. The method of claim 13,
The outer circumferential surface of the movable part has a rough surface. The method of claim 1,
The at least two faces comprise a reflection surface and an anti-reflection surface,
And the antireflection surface and the reflection surface are respectively formed on an outer circumference surface and an inner circumference surface of the rollup blade. 16. The method of claim 15,
And the reflective surface is an outer surface of a light reflective layer formed on the upper electrode. The method of claim 1,
The base plate further comprises a substrate,
The substrate is a light shielding device formed of a transparent (translucent) material. The method of claim 17,
And the substrate is formed of any one or a combination of two or more selected from the group consisting of glass, quartz, plastic, and silica. The method of claim 17,
The lower electrode is any one selected from the group consisting of indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), carbon nanotube (CNT), and a conductive polymer. Light shielding device formed by a combination of two or more. An image sensor;
A base plate disposed on an upper side of the image sensor and including a lower electrode;
A plurality of rollup blades each comprising an upper electrode; And
A driving unit electrically connected to the lower electrode and the upper electrode,
The light transmitting region of the base plate is disposed to correspond to the image sensor,
The plurality of rollup blades are disposed to correspond to the light transmitting area of the base plate,

Each of the plurality of rollup blades includes at least two surfaces having different optical characteristics. 21. The method of claim 20,
And the driving unit drives the plurality of roll-up blades to adjust an amount of light passing through the light transmitting region. 21. The method of claim 20,
One of the two faces is an anti-reflection surface,
And the anti-reflection surface prevents reflection of light incident on an outer circumference surface of each of the plurality of roll-up blades. The method of claim 22,
And the anti-reflection surface includes a black body layer having a multilayer structure formed of different materials. The method of claim 22,
Each of the plurality of rollup blades comprises a light absorbing layer interposed between two or more phase compensation layers. 21. The method of claim 20,
Each of the plurality of rollup blades includes a fixing portion fixed to an outer side of the light transmitting region and a moving portion rolled up toward the fixing portion,
And the plurality of roll-up blades cover the light transmitting area having a circular shape by area division. 21. The method of claim 20,
The two surfaces include a reflection surface and an anti-reflection surface,
And the antireflection surface and the reflection surface are respectively formed on an outer circumference surface and an inner circumference surface of each of the plurality of roll-up blades. The method of claim 26,
And the reflecting surface is an outer surface of a light reflecting layer formed on the upper electrode. Back light unit;
A base plate including a lower electrode and disposed above the backlight unit;
A rollup blade including an upper electrode;
A color filter disposed above the roll-up blade; And
A driving unit electrically connected to the lower electrode and the upper electrode,
The roll-up blade is disposed corresponding to the light transmitting area of the base plate,
The driving unit controls the amount of light passing through the light transmission region by driving the roll-up blade,
And the rollup blade includes at least two surfaces having different optical characteristics. The method of claim 28,
The at least two faces comprise a reflection surface and an anti-reflection surface,
And the anti-reflection surface and the reflection surface are respectively formed on an outer circumference surface and an inner circumference surface of the rollup blade. The method of claim 29,
And the driving unit drives the roll-up blade to selectively operate in any one of a transmission mode using light emitted from the backlight unit and a reflection mode using light incident from the outside and reflected from the reflective surface. The method of claim 28,
The roll-up blades are arranged in plurality in a one-to-one correspondence to each of the pixels of the color filter,
The driving unit is a display device for driving a plurality of roll-up blades individually. The method of claim 28,
The rollup blade includes a fixing portion and a moving portion,
The fixing portion is fixed to the outside of the light transmitting region of the base plate, the movable portion rolled up toward the fixing portion. 33. The method of claim 32,
The driving unit controls the gray level of each pixel by adjusting the average time the movable portion of the roll-up blade is unfolded per frame.

Images